PACIENTES Y MÉTODOS Se realizó un estudio de tipo descriptivo y transversal con pacientes afectados de EM en nuestra área sanitaria. De un total de 519 pacientes con EM definida por neurólogos, tomando como referencia los criterios diagnósticos de McDonald et al [16]. Incluimos en el estudio a aquellos pacientes, con cualquier forma de evolución, que tuviesen una puntuación en la escala EDSS menor o igual a 9 y que se A STUDY OF THE QUALITY OF LIFE IN CASES OF MULTIPLE SCLEROSIS Summary. Aims. Our objective was to study the quality of life (QoL) in a sample of patients with multiple sclerosis (MS) as measured by their scores on the QoL questionnaire SF-36 (Short Form 36 Health Survey) and its relationship with the extent of deterioration of the disease according to the EDSS (Expanded Disability Status Scale). Patients and methods. The QoL SF-36 scale was administered to 78 patients with defined MS. Those who had suffered outbreaks or whose condition had clearly deteriorated in the past 6 months were excluded, and variables such as age, sex and gait disorders, among others, were analysed. Patients were divided into three groups according to their degree of disability on the EDSS scale: group 1 (EDSS 0-3), group 2 (EDSS 3.5-5.5) and group 3 (EDSS > 6). Results. There were significant differences in the mean scores of groups 1 and 3 in several dimensions of the QoL questionnaire (p < 0.05): general state of health, emotional role, physical functioning, physical role and body pain. Differences were also observed in physical functioning and physical role in groups 1 and 2. In group 1, the dimensions with the lowest mean score were body pain and vitality. In group 3, the dimension with the lowest score was physical functioning. The health dimensions belonging to the realm of mental health were the ones that reflected the smallest difference according to the stage, since no statistical significance existed for dimensions such as vitality, social functioning or mental health. Body pain and vitality were more affected at an early stage (group 1) and the effects on physical functioning were stronger at a later stage (group 3). Conclusions. As the disease progresses (EDSS > 6), the dimensions of the QoL SF-36 questionnaire concerning physical health (physical functioning) become affected. Body pain and vitality are the most strongly affected dimensions in the early stages of the disease. These findings should be confirmed in a larger sample in order to provide them with a higher degree of validity.